Part 4

Shell more or less irregular, sub-trigonal, striated or radiated, equivalve, inequilateral, the anterior side shorter and rounded, the posterior sub-truncated; summits well marked; hinge sub-regular, more or less dissimilar, formed by slender, narrow, cardinal teeth, variable in number on each valve, sometimes two on the right and three on the left, and sometimes three on both; these teeth are small, contiguous, parallel, and but little, if at all, divergent exterior; very weak.

Venerirupis perforans. V. nucleus. V. irus. V. exotica. V. distans. V. crenata. V. carditoides.

_V. perforans._ The perforating Venerirupis.

Sub-rhombic, transversely striated, wrinkled on the anterior side; exterior brown, interior white, sometimes tinged with purple.

_V. irus._ The foliated Venerirupis. Pl. 7, fig. 2.

Species longitudinally striated; cardinal teeth two, sometimes three on the right and three on the left.

FAMILY VIII. NYMPHACEA. Ten genera.

This family is divided into N. Solenaria and N. Tellinaria, from their resemblance to the Solen and the Tellina.

N. SOLENARIA. Three genera.

1. Sanguinolaria. Four species.

This genus may be distinguished from the Solen by never having the transverse oblong shape, or the edge of the valves parallel to the base.

Sanguinolaria occidens. S. rosea. S. livida. S. rugosa.

_S. rosea._ The rosy Sanguinolaria.

Semi-orbicular, smooth, shining and convex; near the umbones of a beautiful rose colour, which becomes paler as it descends; acute transverse striæ.

_S. occidens._ The setting-sun Sanguinolaria. Pl. 7, fig. 4.

Oval, a little elongated, very compressed, slightly gaping, valves elliptical, equally rounded at the two extremities, without mark of posterior keel; summits slightly indicated; hinge formed by one or two contiguous cardinal teeth on each valve; ligament projecting, convex; margins not parallel.

2. Psammobia. Eighteen species.

Taken from the Tellina, which it much resembles in form, but from which it differs by not having the irregular plait on the anterior part.

Shell ovate, transverse, slightly gaping; summits projecting; hinge formed by two teeth on one valve, and only one inserted on the other.

Psammobia virgata. P. Ferroensis. P. vespertina. P. florida. P. muculosa. P. cærulescens. P. elongata. P. flavicans. P. squamosa. P. alba. P. Cayennensis. P. lævigata. P. tellinella. P. pulchella. P. aurantia. P. fragilis. P. livida. P. Galathea.

_P. virgata._ The striped Psammobia. Pl. 7, fig. 1.

Species rather gaping, striated longitudinally, the teeth of the hinge considerably effaced.

_P. Ferroensis._ The Ferro Psammobia.

Oblong oval; white, radiated with crimson; finely striated transversely; valves obliquely truncated.

3. Psammotæa. Seven species.

Of the same form as the Psammobia, but differing in the number of teeth, as the left valve of the Psammotæa has only one tooth; sometimes one valve is toothless, while the other has two teeth.

Shell transverse oval or oblong; gaping a little at the sides; one primary tooth on each valve, though sometimes on only one of them; ligament exterior, attached to callosities at the hinge, and without an irregular plait.

Psammotæa violacea. P. zonalis. P. pellucida. P. serotina. P. candida. P. Tarentina. P. donacina.

_P. violacea._ The violet Psammotæa. Pl. 7, fig. 5.

Transversely ovate-oblong, sub-ventricose; transversely striated; purple radiations.

TELLINARIA. Seven genera.

The first five of these genera have one or two lateral teeth, the remaining two have none.

4. Tellina. The Tellen. Fifty-four species.

This genus differs but little from the Donax; its species are numerous, especially in the seas of hot countries; they are found sunk deep in the sand.

There are but few genera that can vie with the Tellina in beauty, variety, or number; some are smooth and polished, some are remarkable for their beautiful radiations, and others are covered with minute striæ and undulations; occasionally the whole surface is covered with imbrications or scales.

They are produced abundantly in almost every sea and in many rivers, but the finest species are found in the pearl-fisheries of Ceylon.

The usual form of the Tellina is broad at one end and gradually tapering towards the other. It derives its name from the Greek word τελειω, to bring to a termination.

Shell of variable form, generally striated longitudinally and very compressed; equivalve, more or less inequilateral; anterior side longer and more rounded than the posterior; offers a flexuous plait or twist at the inferior margin; summits little marked; hinge similar; one or two cardinal teeth; two distant lateral teeth, with a pit at their base in each valve; ligament external.

Tellina radiata. T. unimaculata. T. semizonalis. T. maculosa. T. virgata. T. staurella. T. crucigera. T. Spengleri. T. rostrata. T. lutirostra. T. elliptica. T. albinella. T. margaritina. T. strigosa. T. planata. T. punicea. T. depressa. T. pulchella. T. fabula. T. tenuis. T. sulphurea. T. foliacea. T. operculata. T. rosea. T. chloroleuca. T. remies. T. sulcata. T. crassa. T. lævigata. T. linguafelis. T. rugosa. T. lacunosa. T. gargadia. T. pristis. T. multangula. T. polygona. T. capsoides. T. exilis. T. donacina. T. nitida. T. scalaris. T. psammotella. T. striatula. T. scobinata. T. decussata. T. Brasiliana. T. obliqua. T. umbonella. T. deltoidalis. T. nymphalis. T. solidula. T. bimaculata. T. sexradiata. T. ostracea.

_T. radiata._ The radiated Tellen. Pl. 8, fig. 5.

Shell elongated; posterior side shorter and more narrow than the anterior.

_T. foliacea._ The foliaceous Tellen.

Species transversely oblong; upon the edge of the front side of either valve are rows of serrated teeth, running from the apex to the margin.

_T. bimaculata._ The double-spotted Tellen.

Species orbicular, easily known by answering to its common name.

_T. fabula._ The false Tellen.

Shell very thin, pellucid, and oval; yellowish colour, darker towards the umbo, which is nearly central, pointed and turned a little to one side; anterior side slopes to an obtuse point; posterior side large and rounded; hinge with three teeth in one valve and two in the other.

_T. scobinata._ The rasp Tellen.

Species oval or sub-orbicular, sub-equilateral.

_T. donacina._ The Donax-like Tellen. Pl. 9, fig. 5.

Sub-oval, flattish, semi-striated and semipellucid; hinge with two teeth in one valve and one in the other; pale yellow, radiated longitudinally with pink.

_T. depressa._ The depressed Tellen.

Oval, flat, pointed at the smaller end and slightly reflected; pale yellowish colour, faintly striated concentrically; covered with a pale brown epidermis.

5. Tellinides. One species.

Though this genus bears a great affinity to many others, it cannot be united with any; having lateral teeth, it differs from the Psammobia; by not having the valves twisted, it differs from the Tellina; the valves closing, and having muscular impressions in the interior, render it distinct from the Lucina.

Shell equilateral, rather elongated, almost without the flexuous plait; two cardinal teeth diverging, and two remote lateral teeth, of which the anterior is but little distant from the summit.

_T. Timorensis._ The Tellinides of Timor. Pl. 8, fig. 3.

The only type and species of this genus.

6. Corbis. One species.

This genus was at first classed by Lamarck with the Lucina; but Cuvier, having discovered that the organization of the animals differed, made this a distinct genus, which was adopted by Lamarck.

Shell transverse, equivalve, no flexuosity; apices curved inward, opposed to each other; two primary and two lateral teeth, the posterior one nearest to the hinge; muscular impression simple, valves sometimes convex, strongly ribbed transversely, striated longitudinally, margins serrated and closely interlocking.

_C. fimbriata._ The fringed Corbis. Pl. 8, fig. 1.

Species white, rather thick, oval, a little elongated, almost equilateral; the cardinal and the lateral teeth well marked; the muscular impression anterior, rounded.

7. Lucina. Twenty species.

In the hinge and lateral teeth it much resembles the Tellina, but differs from it in never being flexuous. This genus is more easily characterized by the orbicular, compressed, general form of the shell, than by the dental system, which is sometimes entirely effaced.

Shell compressed, regular, orbicular, sub-equilateral; summits small and pointed, inclined anteriorly; hinge similar, but variable; two divergent cardinal teeth, little marked, and sometimes entirely effaced; two remote lateral teeth, with a pit at the base, sometimes obsolete; posterior ligament more or less sunk; two widely-separated muscular impressions, of which the anterior is narrow and long.

Lucina Jamaicensis. L. Pennsylvanica. L. edentula. L. mutabilis. L. radula. L. squamosa. L. lactea. L. undata. L. circinaria. L. columbella. L. concentrica. L. divaricata. L. carnaria. L. scabra. L. reticulata. L. sinuata. L. pecten. L. lutea. L. digitalis. L. globularis.

_L. Jamaicensis._ The Jamaica Lucina. Pl. 8, fig. 8.

Species lenticular, striated concentrically; the teeth of the hinge variable, and sometimes obsolete.

_L. undata._ The waved Lucina.

Orbicular, thin, convex, undulated with fine irregular striæ; exterior pale yellow, interior white; margin glossy and plain.

8. Donax. The Wedge Shell. Twenty-seven species.

The singularity of form that gave rise to its common name renders it easily distinguished. It very much resembles a wedge, being very broad and thick at one extremity, and gradually tapering towards the other. They vary in colour, but the most general is purple radiated on a white ground, diverging from the beak to the margin; many have an orange tinge, and others a pink hue; the interior generally partakes of the colour of the exterior. There are not, perhaps, two species that have absolutely the same hinge.

The Donax is found buried deep in the sand of the seashore, with the short side uppermost.

Shell sub-trigonal, greater in length than in height, equivalve, very inequilateral; posterior side much shorter than the anterior; summits almost vertical; hinge complex, similar; two cardinal teeth in one or both valves; one or two remote lateral teeth on each valve; ligament posterior, short, and inflated; two rounded muscular impressions.

Donax scortum. D. pubescens. D. compressa. D. cuneata. D. deltoides. D. radians. D. abbreviata. D. triquetra. D. ringens. D. rugosa. D. Cayennensis. D. elongata. D. denticulata. D. granosa. D. columbella. D. veneriformis. D. Australis. D. epidermia. D. bicolor. D. vittata. D. meroe. D. scripta. D. trunculus. D. flabagella. D. cinatinum. D. Martinicensis. D. cardioides.

_D. scortum._ The beaked Donax. Pl. 8, fig. 4.

Species oval, of which the posterior side is sub-truncated; with decussated and muricated striæ.

_D. trunculus._ The common Donax.

Oblong, glossy, finely striated longitudinally, transversely banded and radiated with purple; white, clouded with purple within; internal margin of the valves distinctly dentated or crenulated.

_D. denticulata._ The denticulated Donax.

Species of which the posterior side is truncated; furrowed from the summit to the base.

9. Capsa. Two species.

This genus was separated by Lamarck from the Donax on account of the peculiarity of the hinge.

Capsa lævigata. Capsa Braziliensis.

_C. lævigata._ The smooth Capsa.

Triangular, sub-equilateral, obsoletely striated transversely; covered with a greenish yellow epidermis; inside violet towards the umbones.

_C. Braziliensis._ The Brazilian Capsa. Pl. 8, fig. 7.

Shell elongated, covered with epidermis; equivalve, close; the cardinal teeth reduced to one large sub-bifid tooth on the right valve, placing itself between two very thin ones on the left; ligament external, on the short side.

10. Crassina. One species.

Distinguished from the Crassatella by the position of the ligament, and from the Venus by having only two teeth on each valve; one of them on the left valve projects very slightly.

_C. Danmoniensis._ The Devonshire Crassina. Pl. 6, fig. 1.

Solid, thick, sub-orbicular, sub-equilateral; two very large divergent teeth on one valve, and two very unequal ones on the other; regular parallel grooves and ribs; covered with a yellowish epidermis; inside white; margin broad and plain.

FAMILY IX. CONCHACEA. Seven genera.

This family is divided into Conchæ fluviatiles, fresh-water shells, and Conchæ marinæ, sea shells.

C. FLUVIATILES. Three genera.

1. Cyclas. Eleven species.

The shells of this genus are very small, and are found buried in the mud of fresh waters; the apices or summits are never eroded, and some species are so thin as to be transparent.

Shell covered with a brown epidermis, oval or sub-orbicular, regular, equivalve, inequilateral; summits blunt, contiguous, or turned anteriorly; hinge similar, complex, formed by a variable number of cardinal teeth, and by two remote lateral teeth with a cavity at the base; ligament exterior, posterior, and convex; two distant muscular impressions, without posterior sinus.

Cyclas rivicola. C. cornea. C. lacustris. C. obliqua. C. calyculata. C. obtusalis. C. fontinalis. C. Australis. C. sulcata. C. striatina. C. Sarratogea.

_C. cornea._ The horny Cyclas. Pl. 9, fig. 7.

Species sub-orbicular, convex, thin, pellucid, with fine concentric striæ; cardinal teeth a little variable, always very small, and sometimes obsolete; summits not eroded, covered with a horn-coloured epidermis; interior bluish white.

2. Cyrena. Ten species.

This genus of shells is found in rapid rivers and streams; it was formerly classed with the Cyclas, from which, however, it greatly differs in having three cardinal teeth on each valve, and also lateral teeth. They are thick, solid shells, sometimes of a large size; the apices always eroded or carious.

Shell rounded and trigonal, ventricose, inequilateral; hinge with three teeth on each valve; two lateral teeth, one of which is near the primary ones; ligament exterior, placed on the largest side; in some species the lateral teeth are crenulated, in others they are entire.

Cyrena trigonella. C. orientalis. C. cor. C. depressa. C. Caroliniensis. C. fuscata. C. fluminea. C. violacea. C. Bengalensis. C. Ceylanico.

_C. fluminea._ The river Cyrena. Pl. 6, fig. 7.

Species sub-trigonal or elongated oval; summits decorticated, more anterior; three cardinal teeth, of which the two posterior are forked; exterior greenish brown, interior variegated with white and violet; sulcated transversely.

3. Galathea. One species.

This beautiful shell is found in fresh waters, and is distinguished from the Cyrena by the divergent form of the primary tooth.

_G. radiata._ The radiated Galathea. Pl. 6, fig. 8.

Shell equivalve, sub-trigonal, covered with a greenish epidermis, beneath which the surface is of a milky white, highly polished, with several violet or pale chestnut rays diverging from the apex to the margin; primary teeth furrowed, two on the right valve joined at the base, three on the other valve placed triangularly, the intermediate one being advanced, separate, thick, and callous; the muscular impressions are lateral, and appear double on each side.

C. MARINÆ. Four genera.

4. Cyprina. Two species.

This shell is generally large, resembling the Venus, from which it may be distinguished by having on the front side one impressed lateral tooth, which is sometimes obsolete; the nymphæ or callosities of the hinge large, arched, and terminated near the apices by a cavity, sometimes very deep.

De Blainville says that this genus is intermediary to the Cyclas and the Venus, and contains but one living species; Lamarck makes two, though at first he characterized eight.

Cyprina tennistria. Cyprina Islandica.

_C. Islandica._ The Icelandic Cyprina. Pl. 9, fig. 2.

Shell thick, regular, heart-shaped, covered with dark brown epidermis; white interior; sub-striated longitudinally; apices very strongly recurved anteriorly, and often contiguous; hinge thick, sub-similar, formed by three cardinal teeth but little convergent, and by one remote posterior lateral tooth, sometimes obsolete; ligament very thick, convex, fixed to large, arched, nymphal callosities, preceded by a cavity more or less deep, hollowed immediately behind the summits; muscular impressions subcircular and very distant.

5. Cytherea. Seventy-eight species.

This genus was taken from the Venus, and is easily defined as distinct from it by having four primary teeth on one valve, and only three united on the other, with an isolated cavity, oval and parallel to the margin; the lateral teeth divergent to the summit. In some species the internal margin is entire, having the anterior cardinal tooth with a striated canal or uneven sides; in others the anterior cardinal tooth is entire, without a striated canal; sometimes the internal margin is crenulated or dentated.

Shell solid, regular, equivalve, inequilateral; apices equal, recurved, and slightly projecting; four primary teeth on one valve, of which three are divergent and approximating at the base, and one remote; three primary divergent teeth on the other valve, with a distant cavity parallel to the edge.